1. Field of the Invention
The present invention relates to a food thickening agent and a method for producing a food thickening agent, and more specifically, the present invention relates to a food thickening agent having a long shelf life for use by patients with dysphagia and a method for producing such a food thickening agent.
2. Background of the Invention
Patients with dysphagia have difficulty swallowing food and water without aspirating it. As such, these patients have difficulty swallowing liquid and soft foods. Instead, they must mix such liquid and food with thickening agents.
Currently, manufacturers use modified food starch or xanthan gum to thicken water and other beverages. These thickeners, besides thickening the beverage, carry with them their own flavors, which need to be masked. Manufacturers, including those that use xanthan, use an acid (usually citric acid, acetic acid or others) to cover the flavor. The acid also aids in stability of the product (shelf life). What the acid does though, is bring its own flavor, which is more palatable than the starch or xanthan alone. The acid also has the tendency to yellow the product. This is not noticeable with the starch based material, as it already is cloudy and slightly yellow to begin with. It is very noticeable with the xanthan products, although some of them are naturally opaque as well. As a result of the use of these acids, the product seldom has a look or taste that is natural, especially when trying to reproduce a glass of natural looking and tasting water.
Specifically, it is not uncommon for some food thickeners based on cornstarch to mask the taste and desired consistency of carrots with as little as 5×10−5 weight percent of the thickener/nourishment comprised of the food thickener. A vicious cycle then develops, whereby patients take a sip of the thickened nourishment, then set it aside perhaps to consume later. The longer the liquor sets, the longer amylase (an enzyme in saliva that is transferred to the liquor) has to break down the cornstarch, thereby reducing the thickness (and therefore the usability) of the liquor.
Also, most thickening products currently available, once processed and opened for use have shelf-lives on the order of from eight hours at room temperature, to one week at refrigeration temperatures. This is due to the instability of starch in starch products and moisture content in xanthan products (see discussion below). Thickeners that show the highest ME (end moisture content) have the highest chance of spoilage when compared to thickeners that have low ME, as discussed in Liang et al. Bachelor Engineering Thesis, University of Queensland, 2004.
For example, xanthan gum is utilized as the viscous fluid in the invented mixture. In these cases, water retention is highest, due to the ease in which xanthan's hydroxyl groups form hydrogen bonds with the dispersing media, as detailed in Sopade et al., Eur. Food Res Technol 224:555-560. Hydration or water binding capacity of food is of prime significance for food processors and handlers because sorption properties affect storage, end-use, packaging requirements and certain physical properties.
A need exists in the art for a food thickening agent that, when mixed with food, does not alter the appearance, taste and color of the food, even in thickener loadings exceeding 40 weight percent. The agent should be viable at neutral to basic pH levels. The thickening agent should be inexpensive to manufacture. Also, the thickening agent should have a shelf life of at least 90 days, and preferably greater than 150 days. Finally, the agent should allow patients with dysphasia the opportunity to hydrate from a simple glass of water.